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You are browsing the archive for June 2013 - Page 2 of 2 - Mountain Beltway.

10 June 2013

Monday macrobug: Sarosesthes fulminans

This lovely longhorned beetle was on my house last week. Bugguide.net helped me identify him as Sarosesthes fulminans.

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7 June 2013

Friday fold: South Pass City, Wyoming

Two summers ago, my wife (then my very new wife) Lily and I participated in a two-week workshop for teachers on the energy resources of Wyoming. We also indulged in a visit to a mineral resource site: South Pass City, a site in the southern Wind River Uplift that was the second oldest incorporated town in Wyoming (after Cheyenne). It was a gold mining site, and today it is preserved …

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6 June 2013

Percussion marks on quartzite cobbles in DC

Hey, that quartzite boulder has measles! Or is it bubonic plague? Or maybe it’s just acne? Look closer and see if you can deduce what these things are: These conical fractures are percussion marks. They form when a cobble smacks into another cobble underwater, propelled forward by a powerful current. As the two rocks knock together, the strength of the collision can overwhelm the strength of the bonds holding the …

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5 June 2013

Stone tools of the Piney Branch quarry, DC

Archaeology meets geology in this visit to the Piney Branch valley of Rock Creek Park in Washington, D.C. Cretaceous deposits of cobbles of Cambrian quartzite were quarried by Native Americans and modified into tools thanks to the fact that they break with a conchoidal fracture.

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3 June 2013

Monday macrobug: the 17-year periodical cicada

Brood II. We gots ’em. The noise is so cool….

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2 June 2013

Sidewalk geologic timescales

Saw this educational graffiti on the campus of Carleton College a few weeks ago: Seems like a great way to get students to grasp the relative spans of geologic time.

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